Hello I just got a 1990 Wrangler and my first project is to fix the fuel gauge. The sending unit seems to be working I get 56 Ohms with a half of tank and 115 with a full tank. The tan wire ohms out to the gauge, I get 10.97 volts on the hot wire at the gauge and the ground wire is good. My question is what is the Black and yellow wire coming off the sending unit. Its open to ground . Is it a pull up resistor of some sort or should it be grounded. Thanks for your help.